Multi-armed Archers and Rated ST

Readying a bow to shoot takes two consecutive ready maneuvers, one to draw an arrow and another to pull back the bow (this can be inferred from the fact that a successful fast-draw removes the one second associated with readying the arrow). Basic Lift is defined as the weight that can be lifted above one's head in one second. Based on these two facts combined with the fact that all bows have a Rated ST which is required to use them effectively, it seems reasonable to assume that it is one's basic lift that is being used in that one second of drawing a bow. As stated in the Basic Set, quadrupling the time taken to lift and using two hands lets one lift up to 8 times basic lift, therefore simply using two hands would let one lift up to twice basic lift. All this combined gives the following.

Multi-armed archers (3+ arms) can draw the bow with additional arms, each additional arm used to draw the bow increases the Rated ST of bow they can draw. To find this new Rated ST multiply the basic lift of that ST by 1 + number additional arms). If these additional arms are considered Weak, they only count for 0.5 or 0.25 of an arm as the case may be.

Examples 1: An archer with ST 12 has a basic lift of 29lb. A multi-arched archer using 2 extra arms to draw a bow would have a basic lift of 29 * (1 +2) = 87lb which corresponds to an ST 20.78, this can be rounded up to ST 21. Therefore an ST12 being with at least 4 arms could draw a bow with a Rated ST of 21. 

Example 2: A being with 2 regular arms and 2 weaker vestigial arms (each half as strong as base ST) with ST 16 is drawing a bow with all four of its arms. Its effective basic lift would be 51lb * (1 +0.5 +0.5) = 102lb. This corresponds to ST 22.6, which rounded up means that the being could use a bow with a Rated ST of 23. As can be seen, despite the creature having a high base ST the weaker limbs contribute far less (as expected).

Note: This is assuming that all arms are in a position to draw the bow effectively. For any situation where this may not apply the GM's judgement should be used.

The idea for this post came after watching this youtube video and the act of 4 armed warriors using multiple arms to draw a bow were mentioned. I haven't checked the math thoroughly but from how I've seen more knowledgeable peoples manipulate these figures to seems to work fine. These rules also imply that beings with more arms can in generally lift more than beings with less, whether this is accurate of reality or not I don't know and I'll leave that question for another time. For a game where multi-armed creatures are possible and extra granularity is desired I think these rules would serve adequately.